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30th April 2019, 15:57 | #1 | Link |
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NVidia GPU encode performance differences
Hi,
as I understand the encode engine is separate from the CUDA engine so the CUDA core count does not seem to be a (huge) factor. I suspect there is no big performance difference within a GPU generation and only depends on the number of NVENC, see here. So in theory a Quadro P5000 would be twice as fast as a P4000 and a P2000 would still be as fast as a P4000!? I am wondering how GPU generations differ in encoding speed, e.g. K2000 vs. M2000 vs. P2000 or P4000 vs. RTX4000. Does the number of streams per NVENC roughly translate into fractions of real time for a single stream? Any thoughts are appreciated. Thank you. Last edited by kabelbrand; 30th April 2019 at 16:38. |
30th April 2019, 19:10 | #2 | Link |
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Don't own any card which multiple encoder (NVENC) chips, but I thought that 'the number of encoders' * 'the number of parallel encodings' would be the number of streams you can encode in parallel with that card,....
(Total # of NVENC) * (Max # of concurrent sessions) = 'number of streams that can be encoded in parallel' Never thought that multiple chips could be used to speed up the encoding of a single stream,... |
30th April 2019, 19:13 | #3 | Link |
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I would be surprised if single-stream encoding performance increases on those cards with multiple NVENC engines, but since they are rather expensive, I can't really confirm or deny it officially. Single Stream encoding is already quite fast even on consumer GeForce cards though.
The generation of the card certainly matters however - even more so in quality then speed however. Turing for example made pretty big leaps in quality.
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1st May 2019, 05:04 | #4 | Link |
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@kabelbrand... don't bother, I have an NVIDIA Quadro M4000 but I don't use it to encode 'cause the quality of the resulting encode is not suitable for production as it falls way behind CPU encoding on SSIM/PSNR tests. I use it to scroll the timeline of my NLE smoothly and sometimes with OpenCl when I have to encode in x264, that's all.
For everything else, there's CPU only encoding. |
2nd May 2019, 11:05 | #5 | Link |
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Thank you guys.
Yes, it would not make sense if encoding a single stream uses more than one NVENC. When testing with large Quicktime and MXF files I noticed the limiting factor was not the GPU but I/O and audio encoding so a single NVENC will be sufficient. In terms of quality I guess using the latest generation is the way to go. And even if I don't aim for quality in my current scenario it doesn't hurt if it's the best possible quality at a given bitrate. A few years back I did some tests with a Kepler card and wasn't very impressed with the encode quality but the Pascal card I recently used performed much better in terms of quality. So the Quadro P2000 seems to be the obvious budget choice here and the RTX4000 the encode quality pick. I guess NVidia will also introduce entry level Turing Quadro cards later on. |
2nd May 2019, 20:54 | #6 | Link |
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Unfortunately a recently released low end Turing, the 1650, has the older Volta generation NVENC with quality more similar to Pascal's. You have to be pretty careful when buying a GPU for its NVENC generation.
Edit: Why do you only discuss Quadros for encoding? Wouldn't a 1660 Ti be the budget choice? Do you need lots of concurrent sessions? That seems to be the only difference for single NVENC chip Quadros, with Geforce limited to 2 sessions while Quadros can run as many at once as you want. Curiously none of the RTX cards have multiple NVENC chips.
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2nd May 2019, 22:49 | #7 | Link | |
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Regarding concurrent sessions, that is purely a driver limitation. The implication being that if one is crafty enough, it can be lifted....
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3rd May 2019, 10:42 | #8 | Link | |
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Messing around with drivers or firmware is not an option either. Also I'd prefer a single slot card since this is supposed to go into a 1U 19" enclosure. |
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10th November 2020, 01:51 | #10 | Link |
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It is really interesting that Ampere and Turing dropped interlaced H.264 encoding. The only "N" in that column.
I am happy to see the disappearance of interlaced video but I am surprised that it was worth removing from the new chip.
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10th November 2020, 09:07 | #11 | Link | |
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Fake-interlaced is not possible in all cases. |
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11th November 2020, 21:29 | #12 | Link |
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I took Nvidia dropping support for interlaced video as a sign that interlacing was on its way out, and I was happy about that. No new video created today should be interlaced. Like chroma subsampling, interlaced video is a bad hack to reduce the bandwidth required. We should have stopped using it long before we did.
There is always some pain when dropping an old standard but interlaced video is bad enough that it would take a lot more pain than worry about fake interlaced for bluray compatibility not being possible in some cases for me to think supporting interlaced video is still important. In the worst case software encoding for interlaced H.264 is pretty fast.
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12th November 2020, 18:24 | #13 | Link | ||
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12th November 2020, 20:57 | #14 | Link | |
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Many facilities have large production switchers and baseband routers that are 1.5 Gbps HD-SDI, so even going to 1080p is totally unthinkable without rebuilding the whole facility. Only newer facilities have 3G-SDI or faster for their baseband. Interlacing is here to stay |
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14th November 2020, 01:03 | #15 | Link | ||
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A codec/encoder which can not accommodate yesterday's formats would be unfit for archival. This would affect millions of hours of recorded material, BTW. Not being able to read cuneiform: No entrance to library ;-) rantilein start Why authorities back the in D1 times had opted to save an interlaced picture as one frame, not as two consecutive fields will always look like a sore thumb to me. DCT HF coefficients wasted, motion analysis complicated and with the advent of 4:2:0 chroma destroyed. What a sabotage. HEVC starts to simply treat interlaced just the abovementioned way and demands that reinterlacing be done after decoding fields at rendering. Oh well. rantilein end
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14th November 2020, 11:28 | #16 | Link |
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If you do long-term quality archiving with a GPU encoder, you are doing it very wrong anyway. The only category in which they win is speed, most suitably for real-time processing, not archival.
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16th November 2020, 04:38 | #18 | Link |
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Why are you re-encoding this interlaced video archive though? I assume any interlaced video you are planning to feed a NVENC chip is already encoded as something. If fast and dirty interlaced encoding is OK why not save some time and keep the original video? For the vast majority of customers interlaced video encoding in the hardware is a waste of transistors and dev time.
I do VHS archival and I still capture new tapes but I capture to MagicYUV. For archival I keep it as interlaced H.264, using very slow software encoding. I don't think hardware should worry about archival video, its use case is real time video encoding. As improved as hardware encoding is I still cannot countenance its use for archival.
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16th November 2020, 10:22 | #19 | Link | |
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Best use case I can think of is doing hw-encodes of broadcast DI formats, e.g. AVC-I/XAVC 1080i which is still rather popular. We also still have distribution and contribution encoding that use interlaced AVC that needs to be encoded in realtime, were nvenc could be used as a platform.
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But I think that the biggest market for nvenc is realtime live streaming (with customers like AWS/Elemental), and game streaming, and thats pretty much exclusively progressive, so I guess thats why they are dropping it. Last edited by excellentswordfight; 16th November 2020 at 16:07. |
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16th November 2020, 18:20 | #20 | Link | |
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And in my Gen X generation of streaming video engineers, interlaced has been a huge pain point for us for decades, so we tend to avoid using it at all costs. Interlaced was always a Boomer legacy thing, like Drop Frame timecode. Interlaced almost got dropped back in ATSC 1.0, and that would have been a much better timeline to live in. At least there's no interlaced UHD. And H.264 was the last codec mainstream codec to have interlaced be treated as a first-class citizen with a well-tuned MBAFF. A good 1080i30->1080p60 conversion can look great, is much more compatible, isn't reliant on client-side deinterlacer implementation. and takes maybe 20% more bits max in HEVC last I tested. Heck, in most cases the total experience is probably better in 1080p60 than 1080i30 at the same bitrate. Some more encoding artifacts can be better than deinterlacing artifacts. |
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